(Fristedt, 1885)

Species Overview

Hemigellius pumiceus (Fristedt, 1885) is a thickly lamellate light brown sponge, with a roughly hispid surface and brittle consistency. It is a very coarse Haplosclerid, easily distinguishable from the more supple lamellae of species of the Axinellidae. It is a rare species known only from deep fjord habitats in Norway and Sweden and from cold water coral reefs W of Ireland.

Taxonomic Description

Colour: Light brown; off-white in alcohol.
Shape, size, surface and consistency: (Hemigellius pumiceus BandW) Thickly fan-shaped, lamellate, elongate, not stalked, so apparently broadly attached to the substrate. Size up to 6.5 x 3 x 1.2 cm. Surface rough, strongly hispid, very irregular, with numerous pores (punctate), varying in size between 0.1 and 2 mm. Consistency brittle, but not fragile.
Spicules: (Desmacella pumicea) Megascleres are oxeas, long and slender, slightly curved, ending in a long sharp point: 910-985 x 21-28.5 µm. Microscleres are toxas, very slender, sharply (angularly) bent, with straight legs or with slightly recurved apices, in three size categories: 48-100 x 2 µm, 26-41 x 0.2-2 µm and 6-20 x 0.2-0.7 µm.
Skeleton: (Hemigellius pumiceus BandW) The ectosomal skeleton consists of short spicule tracts which construct an irregular reticulum. The choanosomal skeleton is a strong, somewhat confused reticularion of multispicular primary lines, which are irregularly connected by unispicular secondary lines.
Ecology: Deep water (80-800 m), in sheltered environment.
Distribution: Norway, Sweden, deep ocean habitats W of Ireland.
Etymology: pumiceus (Latin) = like pumice-stone, referring to the consistency.
Type specimen information: No data.

Remarks

This is a clearly recognizable species through its thick-lamellated habit in combination with a coarsely hispid surface, lacking any indication of suppleness which characterizes lamellate Axinellids. In the Arctic there is a second species of Hemigellius, viz. H. arcofer, which is similar in habit but has sigmas as well as toxas for microscleres; the megascleres of that species are only about half the size of those of H. pumiceus.
A suspected third Hemigellius is Gellius stylifer Lendenfeld, 1897, described from 100 m near Rockall, but this has to be confirmed.
Source: De Weerdt and Van Soest (1987).

Kingdom Animalia
Phylum Porifera
Class Demospongiae
Order Haplosclerida
Suborder Haplosclerina
Family Niphatidae
Genus Hemigellius
Species Hemigellius pumiceus

Status in World Register of Marine Species

Accepted name: Hemigellius pumiceus (Fristedt, 1885)

Scientific synonyms and common names

Desmacella pumicea n.sp. Fristedt, 1885: 29, pl. II figs. 9a-d.
Gellius massa n.sp. Arnesen, 1903: 7, pl. I fig. 2.
Gellius arnesenae n.sp. Arndt, 1927: 151; Burton, 1930a: 499; Arndt, 1935: 92, fig. 195.
Gellius pumiceus: Arndt, 1935: 92, fig. 198.
Toxadocia pumicea: Alander, 1942: 27.
Hemigellius pumiceus: De Weerdt and Van Soest, 1987: 314, pl. I figs. 2, 5, 6.

Alander, H., 1942. Sponges from the Swedish west-coast and adjacent waters. Thesis Lund Univ., 95 pp., 16 pls.

Arndt, W., 1927. Kalk-und Kieselschwämme von Curaçao. Bijdr. Dierk., 25: 133-158.

Arndt, W., 1935. Porifera. Tierwelt Nord.-Ostsee, IIIa: 1-140, figs. 1-239.

Arnesen, E., 1903. Spongien von der norwegischen Küste, Monaxonida: Halichondrina. Bergens Mus. Årbok, 1903 (1): 1-30, pls. I-VII.

Burton, M., 1930a. Norwegian sponges from the Norman collection. Proc. zool. Soc. London, 2: 487-546.

Fristedt, K., 1885. Bidrag till kännedomen om de vid sveriges vestra kust lefvande spongiae. K. svensk. Vet.-Akad. Handl., 21 (6): 1-56.

Lendenfeld, R. von, 1897. Notes on Rockall island and bank. Reports. On the Spongiida. Trans. roy. Irish Acad., 31 (3): 82-88

Weerdt, W.H. de and R.W.M. van Soest, 1987. A review of North-Eastern Atlantic Hemigellius (Niphatidae, Haplosclerida). 309-321. In: J. Vacelet and N. Boury-Esnault, eds. Taxonomy of Porifera. Springer Verlag, Berlin, Heidelberg. NATO-ASI Series, G13: 1-332.

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